Device for pressing pieces of sheet metal

ABSTRACT

A DEVICE FOR HYDRAULICALLY PRESSING SHEET METAL IN WHICH A FLEXIBLE DIAPHRAGM EXTENDS TRANSVERSELY THROUGH A CHAMBER FORMED AT ONE END OF A CYLINDER BODY TO DIVIDE THE CHAMBER INTO TWO CHAMBER SPACES. THE SHEET METAL TO BE PRESSED IS SANDWICHED IN ONE OF THE CHAMBER SPACES BETWEEN THE FLEXIBLE DIAPHRAGM AND A MATRIX IN THE ONE CHAMBER SPACE, THE OPEN END OF WHICH IS CLOSED BY A CLOSURE MEMBER CLAMPED BY RELEASABLE CLAMPING MEANS AGAINST THE ONE END OF THE CYLINDER BODY. THE OTHER CHAMBER SPACE COMMUNICATES WITH A BORE IN THE CYLINDER BODY IN WHICH A PISTON IS RECIPROCABLY ARRANGED AND PRESSURE FLUID IS FIRST FED INTO THE BORE PORTION COMMUNICATING WITH THE OTHER CHAMBER SPACE AND THEN AGAINST THE PISTON FACE FACING AWAY FROM THE DIAPHRAGM TO PRESSURIZE THE FLUID.

W 2, 1971 K. E. KRAMER 3,6M,@3

DEVICE FOR PRESSING PIECES OF SHEET METAL Filed Juno 5, 1969 3 Sheets-Sheet 1 inventor": l\ L A05 GIWILHE R W 26, W K. E. KRAMER I 3,614,333

DEVICE FOR PRESSING PIECES OF SHEET METAL Filed June 3, 1969 5,Shoots-Shoot 2 W71 K. E. KRAMER DEVICE FOR PRESSING PIECES OF SHEET METAL S Sheets-Shoot 3 Filed June 5, 1969 Inventor ALAUS YNZAMEAJ 3,614,883 DEVICE FOR PRESSING PIECES OF SHEET METAL Klaus E. Kramer, 14 Kommandantenstr., 45 Berlin, Germany Filed June 3, 1969, Ser. No. 830,161 Claims priority, application Germany, June 4, 1968, P 17 52 485.5 Int. Cl. BZld 22/12 US. Cl. 72-63 8 Claims ABSTRACT UP THE DISCLOSURE A device for hydraulically pressing sheet metal in which a flexible diaphragm extends transversely through a chamber formed at one end of a cylinder body to divide the chamber into two chamber spaces. The sheet metal to be pressed is sandwiched in one of the chamber spaces between the fiexible diaphragm and a matrix in the one chamber space, the open end of which is closed by a closure member clamped by releasable clamping means against the one end of the cylinder body. The other chamber space communicates with a bore in the cylinder body in which a piston is reciprocably arranged and pressure fluid is first fed into the bore portion communicating with the other chamber space and then against the piston face facing away from the diaphragm to pressurize the fluid.

The invention relates to a device for pressing or forming pieces or articles of sheet metal by means of the pressure of a liquid, in which the pressure delivered by a piston acts on a membrane, which in turn presses the work piece against the matrix, abutting against a matrix support and with a connecting part, which holds this support together with the main pressing body.

Therein the cylinder body is provided with a flange, the matrix support is formed as an enclosure with a flange and the connecting part is a circular clamp embracing the flanges. The piston is mounted vertically upwardly in the cylinder against the matrix or the working tool and a membrane or a rubber bolster is placed between the pressure transducing means above the piston and the work piece.

To open that circular clamp, it is divided into two parts which are slidable on a vertical axis.

The object of the invention is an advantageous further development of this device to an individual tool or tool machine, which is simple, to be put into practice at any place and which can be used for making products of high quality by a single unskilled operator.

According to the present invention it is proposed, that the device is a handy and easily transportable unit connectable to a supply of electric current, especially to a Wall socket of such supply and that it comprises a working table formed as part of a housing which supports the device for pressing, a circular clamp mounted upon the working table, a pumping apparatus for the pressure transducing means, a control switching circuit within the housing and wherein the device for pressing is formed such that its actuating means and the pressure of the transducing means and the size of the pump are such that device can work nearly free of ballast and will produce only the force for the effective work.

Since according to the idea of the present invention and its features no excessive masses are moved, there is necessary only a small amount of energy, a separate connection to a power source of the electrical mains is not needed. The new device allows its employment in small business or work on a small scale, e.g. in arts and craft.

According to the invention it is essential that the work- 3,bl4,883 Patented Get. 26, 197i ing space of the pressing device initially is filled quickly by the pressure fluid furnished by the pump, the enclosed pressure fluid being then further compressed by a stepped piston. The pressure to be reached is sometimes greater than the pressure of the pump in the ratio of its transverse or cross-section faces.

With the features of the embodiment of the invention there is reached a better and quicker or rapid building up of compression on essential higher pressure amounts with a smaller employment of machinery and energy and at the same time an improved handling of the unit or machine.

With this, the technical progress is obtained, that work pieces of sheet metal are manufactured considerably quicker and with a greater precision of forming and that even with important smaller machines greater work pieces, which do not need any subsequent or additional work, can be produced.

These and other advantages features of the invention are to be understood from the following description.

One embodiment of the device of the invention is described in connection with the accompanying drawings.

In the drawings there are shown in:

FIG. 1 the device in an elevational sectional view, in FIG. 2 details of the device of FIG. 1 and in FIG. 3 the electrical circuitry for operating the device according to FIG. 1 and FIG. 2.

Referring now to FIG. 1 of the drawings, the improved device comprises a housing or framework 20 with its upper side formed as a working table. At this end a tool support plate 19 is mounted on the housing 20. The plate 19 has a hole, in which fits the pressing cylinder 1' of the pressing device. The cylinder 1 is closed on its upper side by closure member 3' held by a circular clamp 4'. On its lower side it is closed by bottom plate 18. The circular clamp 4' consists of two parts 4a and 4'1). The part 4']; is rigidly connected with the cylinder 1' at 4c, while the part 4'11 of the circular clamp 4 is rigidly connected to the closure member 3' at 4'0! preferably with a two-component adhesive. The parts 3' and 4a are together swivelmounted upon the tool support plate 19 and the cylinder 1' slidable on a vertical axis.

In the cylinder 1 there is provided a central bore as the cylinder space 8, in which the piston 2 is fitted. The cylinder space 8 and its matched piston 2' are stepped down to a smaller diameter in the upward direction. The piston 2 can be held by a release spring 9 on its lower side.

With the stepped cylinder bore and the stepped piston 2' there are provided the cylinder divisional spaces 8a, 8b and 8c, in which pressure transducing means, such as oil or glycerine, is present.

Both the two diameters of the stepped piston and the impetus reached are chosen so that the expansion of the working space 6, with the building up of the pressure, occurring and the diminutation of the volume of the normally thought as incompressible pressure transducing means, occurring at the same time, just will be reached with security by the impetus volume of the small piston. This is attainable with the geometric proportions of the corresponding parts in FIGS. 1 and 2 of the drawings.

Referring now to FIG. 2, there are illustrated enlarged details of the cylinder 1 and its space 6'.

At the border of space 8a to space 6' there is provided a circular groove l'a, in which the annular rim 5c of the member 5b is located in stressed condition and held therein in a sealed manner by the pressure of the fluid in the space 6'.

On the upper side of the membrane 5b there rests a rubber bolster 5b, which forms a working plate. The raw material such as cut sheet metal 16 will be put or laid upon the working plate 511.

With larger articles a round disk is used, cut from sheet metal upon which the sealing ring 11' is placed as a maintenance or restraining ring.

With the building up of the pressure in space 6 the sheet metal 16 is bent over the circular edge 11a of the ring 11', so that it is stretched like a membrane. At increasing pressure the raw material tears off along the sharp edges 17a of the cutting mask 17.

If only forming is desired, e.g. a bending or bevelling is to be performed, there are used masks 16, the edges 17a of which are rounded.

The sealing ring 11 consists preferably of a non-metalic material, like artificial or natural material. It has been found, that hard polyvinylchloride, wood, Bakelite, moulded plastic compound and similar easily workable pressure resistant materials are suitable for that purpose and have the advantage of being inexpensive.

If the sealing ring 11 is made from a plate with the diameter of the working space 6, it will be a simple item to keep in stock because it is a standard part, out of which the contour of the work piece only is to be cut off. The corresponding circumferential recess should be equally somewhat greater than that of the working tool 17.

To provide for a simpler handling it is useful to connect the sealing ring 11 and/or the working tool 17 on its upper faces with the metal plate.

Within the framework 20 there is installed a container 21 for the pressure transducing means together with a pump 22 and with a motor 23 driving the pump.

A feed line 24 leads from the pump 22 to the magnetic valves 25 and 26. These valves are formed as three-wayvalves.

A line 27 leads from the valve 25 to the cylinder space 811, in which it enters just above the upper edge of the piston 2 at 270, when the piston is in its lowest position. The piston 2' closes this opening on its upward stroke and separates the line 27 from the cylinder space 8a.

A line 28 leads from the valve 26 to the cylinder space 80.

The return lines 31:: and 31b lead from the magnetic valves 25 and 26 to the oil supply container 21.

Furthermore a line 31 for leaking oil is provided from space 8b.

The magnetic valves 25 and 26 are activated by pressure switches 32 and 33. An electric switch 34 serves for switching on the machine.

The structure of the electrical circuitry for the machine is schematically shown in FIG. 3. It consists essentially of an automatic switching device 35, which is released by the switch 34 (FIG. 1).

The automatic switching device 35 is meant to be consisting of the switching circuits 50, 51 and 52.

The automatic switching device 35 is connectable to the electrical line of the mains. Between the terminals 53 and 54 there is provided the switching circuit 51, which comprises the following elements connected in series: the emergency-off-key 55, the overload protection contact 56, the protection-on-contact 57, the bimetal protection contact 58, the pressure switch 33, the off-key 59, the on-or starting switch 34 and the motor remote-control switch 60.

The opening contact 56 is associated with the closure 3, which is connected to a handling member, which can be a handle 4'e or a motor or the like.

In the switching circuitry 52 the windings of the magnetic valves 25 and 26 are in connection with one auxiliary remote-control switch 61 and with the pressure switch 32. In this switching circuitry 52 there are also provided the contacts 61a and 61b of the auxiliary remote-control switch 61 and the contacts 60a, 60b and 600 of the motor remote-control switch 60 as well as the lamps 62 and 63 as the indication means for the operation conditions of the machine.

To the motor remote-control switch 60 are associated the contacts 60a, 60b and 600, of which the contact 60a switches the motor 23. The contact 60b is in parallel to 4 the switch 34 and serves for self-maintenance of the motor remote-control switch 60. The contact 60c switches the magnetic valve 25 and the lamps 62 and 63.

Associated with the auxiliary remote-control switch 61 there are the contacts 61a and 61b, of which the contact 61a serves as self-maintenance of the auxiliary switch 61 and the contact 61b switching the magnetic valve 26.

The automatic switching circuitry 35 is released or switched on by the pressure switch 34 and switches off automatically by the pressure switch 33 provided in the switching circuitry 51 and 52.

Referring to FIGS. 1 to 3, the operation of the machine will now be described:

The machine is to be connected by the mains plug (terminals 53 and 54) to the wall socket of the normal light mains and the circular clamp 4 is opened manually or mechanically by swivelling out the circular clamp part 4a fastened to the closure 3 by means of the handle 4'e. Then a piece of the raw material 16 to be formed will be put upon the membrane or rubber bolster 5a. Further, the cutting mask or the working tool 17 and the restraining ring 11 will be placed on the previously mentioned parts. The circular clamp 4 is then brought to the closed or working position. Thereby the opening or on-contact 56 will be closed, as the lamp 63 for indicating Ready For Operation begins to light up.

By pushing the starting switch 34 one cycle of operation is initiated, when the contacts 55, 56, 57, 58, 33 and 59 are closed. If one or more of these contacts are opened the pushing of the starting switch 34 remains ineffective. With all contacts closed the motor remote-control switch 60 with contacts 60a, 60b and 600 will be energized.

The contacts 60a switch on the motor 23. The contact 60b in parallel to the starting switch 34 serves for the self-maintenance of the motor remote-control switch 60, so that the button of the starting key 34 may be pushed only during a short time. The contact 600 changes from the position, in which it switches on the lamp 63 for Ready For Operation, to its other position in which the magnetic valve 25 connects the feed line 27 with the spaces 8a and 6, thereby the lamp 62 for Operation is switched on.

If the pressure in the spaces 6 and 8 has reached its first maximum pressure, adjust-able with the pressure switch 32, the auxiliary remote-control switch 61 with its contacts 61a and 61b will be energized.

The contact 61a switches the magnetic valve 26 to connect the feed line 28 to space 80. The piston 2 is moved upward. If its upper edge has reached the highest point of the opening 27a of the line 27, it will be separated from space 8a. The spaces 8a and 6' are now closed, so that upon further up-stroke of the piston 2' in these spaces there will be built up an increasing pressure, which is in each instance greater than the pressure in the space 8c in a ratio of the working or cross-section faces of the two piston sections. When the pressure in space 8c has reached a second maximum pressure, adjustable with pressure switch 33, the switching circuitry 51 will be interrupted. Herewith the motor remote-control switch 60 is deen ergized.

The contacts 60a switch off the motor 23. The contact 60b is opened and hereby interrupts the self-maintenance of the motor remote-control switch 60. The contact 600 changes to its inactive position or that of rest, so that the magnetic valve 25 will be switched on backward run of the pressure fluid out of the spaces 8a and 6, as the lamp 62 for Operation goes out, and the lamp 63 for Ready for Operation lights up.

Upon interruption of the switching circuitry 51 the auxiliary remote-control switch 61 is also deenergized. The contact 61a will be opened and switches the magnetic valve 26 on backward run out of the space 80. The contact 611) will be opened, so that the self-maintenance of the auxiliary remote-control switch 61 is interrupted as well.

Thus, the initial position of the automatic switching device 35 is obtained and a new working cycle may be initiated.

For removing working piece, waste and working tool from the tool machine the circular clamp part 4a is swivelled outwardly. Thereby the switching circuit 51 will be interrupted by opening contact 56, so that the lamp 63 for Ready For Operaton goes out.

With placing a new cut and a working tool, which may be the one previously used or another, the circular clamp 4' will be closed, thereby the lamp 63 showing Ready For Operation lights up again. With this, a new working cycle may be released by pushing the button of start key 34.

While a particular embodiment of the present invention has been illustrated, it should be clearly understood that it is not limited thereto since many modifications may be made in the several elements employed and in their arrangement and it is therefore contemplated by the appended claims to cover any such modifications as fall within the spirit and scope of the invention.

What is claimed is:

1. A device for hydraulically pressing sheet metal blanks comprising, in combination, a cylinder body having opposite ends and being formed with a bore extending from one of said ends into said body, said body being further formed with a chamber open at the other end of said body and communicating with said bore; flexible diaphragm means extending transversely through said chamber and having a peripheral portion anchored in said body, said diaphragm means dividing said chamber in a first chamber space communicating with said bore and a second chamber space; matrix means received in said second chamber space spaced from said diaphragm means so that a blank to be pressed may be placed between said diaphragm means and said matrix means; closure means abutting against said other end of said body for closing said open end of said chamber; releasable clamping means connected to said body and said closure means and being movable between a clamping position clamping said closure means against said other end of said body and a releasing position; a piston reciprocable in said bore between a rest position and an active position in which an end face of said piston is closer to said diaphragm means than in said rest position; and means for feeding pressure fluid into the space between said end face of said piston and said diaphragm means while said piston is in said rest position and then into said bore against the face of said piston facing away from said end face to thereby move said piston from said rest to said active position to exert presssure on said fluid and to flex said diaphragm means with the sheet metal thereon against said matrix means.

2. A device as defined in claim 1, wherein said bore in said cylinder body is a stepped bore having a first bore portion at said one end of said body and a second bore portion of a smaller cross section than said first bore portion, and wherein said piston is a stepped piston having a first and a second piston portion respectively slidably guided in said first and second bore portions.

3. A device as defined in claim 1, wherein said means for feeding pressure fluid first into said space between said end face of said piston and said diaphragm means and then against the face of said piston facing away from said end face comprise pressure switch means for sensing the pressure in said space and valve means cooperating with said pressure switch means for automatically stopping feeding of pressure fluid into said space when the pressure in the latter reaches a predetermined pressure and for then automatically feeding pressure fluid against the face of said piston facing away from said end face to move said piston from its rest to its active position.

4. A device as defined in claim 3 and including further pressure switch means cooperating with said valve means for automatically stopping feeding pressure fluid against said face of said piston upon build up of a predetermined pressure against said face of said piston.

5. A device as defined in claim 1, wherein said feeding means comprise a pump, electric motor means for driving said pump and switch means for starting said motor means, and including circuit means connected to said switch means for preventing starting of said motor means when said clamping means is said releasing position.

6. A device as defined in claim 1., wherein said clamping means comprises a two-part clamping ring, one part being fixed to said cylinder body and the other to said closure means.

7. A device as defined in claim 1, wherein said matrix means comprises an annular member having an endless cutting edge facing said diaphragm means and a second member within said annular member and having a contoured face facing said diaphragm means so that a blank placed between said diaphragm means and said matrix means may be cut by said cutting edge and deformed to said contoured face.

8. A device as defined in claim 7, wherein said annular member is formed from non-metallic easily machineable pressure resistant material.

References Qited UNITED STATES PATENTS 442,246 12/1890 Chapman 72-6l 3,033,143 5/1962 Grankowski 72-63 3,376,723 4/1968 Chelminski 72-63 3,396,561 8/1968 Day 72--63 FOREIGN PATENTS 200,771 1/1966 Sweden 72-63 RICHARD J. HERBST, Primary Examiner 

